In the manufacture of semiconductor structures it is often necessary to subject the structures to high temperature annealing. For example, a high temperature annealing step is often necessary to drive into a substrate dopants disposed close to a surface portion of the substrate and to establish the desired depth of the doped region. In many such processes this high temperature treatment takes place in a dry or steam oxidizing ambient in order to avoid the problems associated with the accidental presence of small amounts of oxygen in the annealing chamber (caused either from room air pressure leaks into the annealing chamber or caused from its presence as an impurity in the inert gas introduced into the chamber) which can produce the normally volatile SiO. However, unless oxidation prevention layers are formed over all oxidizable parts of the structure, many portions of the structure will be oxidized and will require etching to remove the unwanted oxides. Furthermore, depending on the type of materials exposed to oxidation and the degree to which the materials are protected from oxidation, some regions may be oxidized faster than others forming oxide layers with different thicknesses. For example, a silicon layer exposed to a high temperature oxidizing ambient will oxidize faster than another silicon layer which is already covered by a thin silicon dioxide layer. This makes the removal of the new silicon dioxide layer difficult because the same etching solution will remove new and old silicon dioxide material at the same rate. In some cases this may result in the overetching of underlying oxide layers which may in turn cause damage to the underlying structures.